Process of manufacturing furfural



Nov. 12, 1929.

6. S. MINER ET AL PROCESS OF MANUFACTURING FURFURAL Filed Sept. 7. 1922Patented Nov} 12, 1929 UNITED STATES PATENT OFFICE cm a. mm, orcmoaeo,,mmors, am) minors J. snowman, or cause mine, IOWA, assmnoas rcoma oars comranx, or orucaeo, rumors, a con-roan:

MESS OF FUBIURAL Application fled September 7, 1922. Serial Io. 588,795.

Our invention relates to improvements in processes for manufacturingfurfural and volatile organic materials and ithas special reference tosuch a process as may be practiced on a commercial scale to produceeconomically the aforesaid materials.

More particularly our present invention pgrtains to a rocess formanufacturing fural and the 'ke from roughages such as out hulls, ricehulls, cotton seed hulls, corn cobs,

etc. whereby furfural may be produced and recovered in quantitiescommensurate with commercial requirements and economical production.

Heretofore furfural has been generally produced by processes thatresulted in the recovery of only a comparatively small amount offurfural. Such processes have involved immersing certain roughagematerials in a strongly acid liquid and then heating this resultantliquid mixture, which comprises a.

substantially large water content, either with or without subjecting itto pressure, thereby ensuring a chemical reaction which 're-' sults inthe procurement of furfural. But

furfural produced as described above is mixed with such extremely largequantities of water as to render the separation of the furfural from thereaction mixture an extremely tedious and expensive process.

" Unless the furfural is removed from this reaction mixturesubstantially as fast as it,

is formed the furfural, under the conditions present, will be rapidlydestroyed or decomposed and, as a result, the furfural production isconsiderably decreased.

By means of our present invention, we are able to increase appreciablythe yield of furfural from roughage material and, at the same time,reduce considerably the cost of manufacture. We have found that ifroughage material, such as oat hulls, is merely dampened with an acidliquid and subsequently exposed to heat and pressure, a substantially hih yield of furfural results which is capa 1c of being'separatedin moreconcentrated form than in previously known processes, whereby the costof producing this 4 product is greatly minimized. Again, 1n accordancewith our present process, we are reaction mixture thereby thoroughlyexposing the body of the mixture to the action of the steam in a finestate of subdivision and then withdrawing therefrom the steam whichserves as a carrier for the furfural into a con-s denser. As aconsequence, the furfural is volatilized and removed from the reactionchamber substantially as quickly as it is formed. By reason of thisremoval of the furfural very little furfural is decomposed or destroyedin the reaction chamber and this results in a very high yield offurfural.

Other advantages resulting from the practice of our improved processwill be apparent from the following description to which reference maynow be hadfor a more complete understanding of the nature and scope ofour invention.

Since we employ roughage material that preferably has been merelydampened with and acid liquid, less steam is required than in otherprocesses heretofore practiced for a similar purpose. Again, in ourpresent process less acid is-r ulred and a saving in acid and .inneutralizing material therefore results. We have ascertained that, inaccordance with our invention, the increased yield of furfural accruingby reason of the use. of a lesser amount 'of acid liquid is considerablygreater than could be anticipated, since such mcrease in the yield offurfural is not in proportion to the acid concentration but greatly inexcess thereof. In other words,

the enhanced yield of furfural resulting from a decrease in the li uidcontent comprised in the mixture with t e roughage material is excessthereof.

, furfural being formed so as to minimize the descri tion anddestruction or decomposition of furfural which occurs when furfural isexposed for any substantial tions necessary or its formation. Furfuralmay then be procured by our in large quantities, se arated in big erconcentratrons and pr need with lower consumption of steam than by the.methods heretofore known and practiced. v

For a better understanding of our mven- Zion reference ma be had to thefollowinge accotlgganying drawing in which we have illustra one form ofapparatus for practicing. our present inven-.

tion.

In ractieing our process, we have found the fo lowing mixture and modeof procedure satisfactory, but it is to be understood that plicity ofjets) is admitted to the cooker we are not to be limited to the s ificcharacter or proportioningv of ingre dignts or to the definite limits oftime and pressure which we mention herein as being ver suitable. Inpracticing our method, we emp oy preferably an apparatus of the generalcharacter diagrammatically illustrated in the single figure of theaccompanyingdrawing wherein is illustrated a rotary steam jacketdigester or autoclave 1 of an well known t e that is preferably provi edwith a plura ity of pipes or steam inlets 2 in order .to pass a verylarge number of fine jets of steam through the reaction material 3undergoing treatment. Into such a digester we put substantially 3000pounds of oat hulls uniformly impregnated with a mixture of about 750pounds of water and about 56 ounds of sulphuric acid (95% strength). edigester is then closed and rotated and if it is not sufficientlyheatedffrom a rior treatment, steam is admitted into the jac et 4 oftheautoclave for such length of time as is necessary to raise thetemperature of the autoclave to approximately that of steam at {roundspressure. After the temperature of t e mixture within the autoclave hasbeen substantially raised, steam ,(in the form of a multithrough theaforesaid pipes or inlets 2and, as a consequence, the reaction mixture 3comprising the oat hulls becomes thoroughly ad-' mixed therewith. Thesteam pressure within the digester is raised to about 60 pounds persquare inch. When the steam pressure within the autoclave a proximatesthis value, the valve 5 of the e ust line'leading to the condenser 6 isopened sufliciently to or five hours. After this period of time, all. ofthe steam containedswithin the autoclave is blown off into the condenserand additional "steam at atmospheric pressure may then be riod tel-.11reaeuon eondipassed throu h the oat hulls to remove the residual furral. However, this last step is frequently not necessary.

The steam condensed in the condenser 6 neutralized in any suitable way,preferably 'by adding hydrated lime or any other alkaline orneutralizing material, to ensure complete neutralization of the acid,andthen is distilled to recover the furfural which amount tosubstantially more than 10% b wei ht of the total amount of oat hullsim- I tla y placed within the digester.

Ourpresent process contemplates tinuous remova of the furfural from thereaction mixture, whether acid is added or not, since we eliminate thepossibility of may substantial amount of furfural being ecomposed ordestroyed by immediately removing the con- .3

it after formation from the digester or autoclave to the condenser.vious that our improved method will be Therefore, it is obhighlyadvantageous when used both in the I absence of and 1n the presence ofan added acid content in the reaction mixture.-

From the foregoing, will-.be apparent that the mixture initially placedwithin the digester preferably comprises roughage material that has beenmerely dampened w th -an acid liquid mixture. Of course, while we havespecified oat hulls as ourv preferred rougha e material, it is to beunderstood that our mefiiod is applicable with advantageous resultsto-the use of other furfural yie ding roe.

material, such as cotton seedhulls, rice hulls A and the like. Again, itis obvious that acids other than sulphuric acid ma be used and that thepro ortions which we ave indicated above ma h I ewise be varied.

Oat hu furfural may be procured in accordance with the hprocess of thispresent invention, are

big y desirable because they are resilient as roughage material fromwhich I and do not pack within' the. autoclave or digester when they aredampened ,and when 4 the digester is rotated during the processing ofthem. The mass of oat hulls is extremal porous and, consequentl ermitsthoroug admixture therewith o t e liquid which dampens the mass. Again,by reason of the porosity of the mass 0 oat hulls, the carrier steam orgas is permitted to'penetrate the lac mass. thorou hly, thereby bringingthe carri'erfor the urfural, as it is produced, into intimate contactwith all parts of the mass of oat hulls.

While the term reaction mixture as used herein applies generall to themerel dam ened mixture of liqui catal st an roug age material in whichthe fur ural is formed, this term reaction mixture in its most s ecificsense ap lies to the mixture of liqu1d, catalyst (w en and if used) anddissolved pentose, the constituents that are 1 mmediately involved inthat reaction which results in the formation of furfural. In our processthis reaction mixture may be con sidered as being contained within alarge number of relatively small particles of roug age material andthese articles of material are continually surroun ed by steam which isthe active agent in removing the furfural from the liquid in thedampened reaction mixture substantially as quickly as it is formedtherein.

While we have herein described our method of practicing our invention,it is to be understood that our invention is not to be limitedexcept inaccordance with the appended claims.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent is 1. The process ofmanufacturing furfuralwhich comprises impregnating a mass of roughage material with a quantityof acid liquid sufficient merely .to dampen said roughage material, andsubjecting this reaction mixture to the conjoint action of heat,pressure and a continuous supply of steam for removing the furfural fromthe liquid 1n the dampened reaction mixture substantially asquickly asformed. p

2. The process of manufacturing furfural which consists in impregnatinguniformly a mass of roughage material with a quantity of dilute sulfuricacid suflicient merely to dampen said roughage material, and subjectingthis roughage material to the con o1nt action of heat, pressure and acontinuous supply of steam for removing the furfural from the reactionmixture as formed while maintaining said massof roughage material in adampened state.

i 3. .The process of manufacturing furfural which consists in uniformlyimpregnating a mass of oat hulls with a quantity of dilute sulphuricacid. sufiicient merely to dampen said mass of oat hulls, and subjectingthis reaction mixture to the conjoint action of heat, pressure and acontinuous supply of steam for removin the furfural from the reactionmixture as ormed.

4. The process of manufacturin furfural which comprises mixing a mass 0roughage material with a furfural forming catalyst and a quantity of aliquid sufficient only to dampen said mass, and subjecting the same i tothe action of heat, ressure and a continu- ,ture the furfural as formed.

6. The method of manufacturing furfural which com rises submitting adampened furfural yiel ing mass of material and a furfural formingcatalyst to the simultaneous action of pressure and a continuouslysupplied current of gas while maintaining said mass in dampenedcondition, said gas serving to maintain the reaction temperature and asa carrier for removing the furfural from the liquid in the reactionmixture.

7. The process of manufacturing furfural which comprises dampening amass of roughage ,material with an acid liquid, and subjecting thisreaction mixture throughout to a contlnuous flow therethrough of steamin a fine state of subdivision in order to intermix thoroughly the steamwith the reaction mixture thereby volatilizing and removing the furfuralfrom the liquid in the dampened reaction mixture substantially asquickly as formed, said mass being maintained in a dampened condition.

8. The process of manufacturing furfural which comprises merelydampening a mass of roughage material with a quantity of liquid, mixingtherewith a furfural forming catalyst and still maintainin the mass indampened condition, and sub ecting this reaction mixture to the actionof heat, pressure and a continuous flow therethrough of steam in a finestate of subdivision in order to intermix thoroughly the steam with thereaction mixture thereb volatilizing and removing the furfural rom theliquid in the dam ened reaction mixture substantially as quic ly asformed.

9. The process of manufacturing furfural which comprises admixing a massof dampened roughage material with a non-volatile furfural formingcatalyst, and subjecting this dampened roughage material throughout to acontinuous flow therethrough of steam under pressure in a fine state ofsubdivision in order to'intermix thoroughly the steam with the reactionmixture thereby volatilizing and removing the furfural from the liquidin the dampened reaction mixture substantially as quickly as formed,said mass being maintained in a dampened condition.

10. The process of manufacturing furfural which comprises admixing amass of dampened roughage material with an acid furfural formingcatalyst and still maintaining the mass in dampened condition, andsubjecting this mixture to the conjoint action of heat, pressure and acontinuous flow therethrough of a gas which is admittedin a fine stateof subdivision in order to intermix thoroughly the gas with the reactionmixture thereby volatilizin and removing the furfural from the liquid inthe dampened reaction mixture.

substantially as quickly as formed.

quickly as formed, said mass being maintained in dampened conditionthroughout the reaction period.

p In witness whereof, we have hereunto subscribed our names.

CARL S. MINER. HAROLD J.BROWNLEE.

11. The process of manufacturing furfural.

which comprises admixing a mass of oat hulls with a quantity of an acidliquid sufiicient only to dampen said mass, and subjecting this reactionmixture to the conjoint action of 7 heat, pressure and a continuous flowtherethrough of steam in a fine state ofsubdivision in or er to intermixthoroughly the steam with the reaction mixture thereby volatilizing andremoving the furfural from the liqui in the dampened mixturesubstantially as quickly as formed, while maintaining the mass indampened condition.

12. The process of manufacturin furfural which comprises admixing a mass0 oat hulls with a liquid comprising sulphuric acid in order merely todampen said mass, and subjecting this dampened mass to the action ofheat, pressure and a continuous flow therethrough of steam in a finestate of subdivision in order to impregnate thoroughly the reactionmixture while maintaining said mass of oat hulls in a dampened state andto remove the furfural therefrom substantially as quickly as formed.

13. The process of manufacturing furfural which comprises mixing a massofroughage material with a quantity of li uid sufiicient only to dampenthe mass,su jectin this dampened roughage material to the actionof heatand pressure while maintaining said mass in a dampened condition, andvolatilizing the furfural and withdrawing it from the liquid in thedampened mass substantially as quickly as formed.

- 14. The process of manufacturing furfural which comprises mixing adampened massof I maintaining said mass ina dampened condition, andcontinuously volatilizing and removing the furfural from the liquid inthe dampened reaction mixture substantially as 7 Patent No. 1,735,084.

CERTIFICATE OF CORRECTION.

Granted Norember l2, 1929, to

CARL s. MINER ET AL.

It is hereby certified that error appears in the above numbered patentrequiring correction as follows: In the grant, title of invention shouldread "Process of Manufacturing Furfural" instead of "Processes ofManufacturing Furfural"; page 4, line 3, claim 10,. for "and" read"while"; same page, line 23, claim 11, before the word "mixture" insertthe word "reaction"; and that the said Letters Patent should be readwith these corrections therein that the same may conform tonthe recordof the case .in the Patent Office.

Signed and sealed this 14th day of January, A. D. 1930.

\ V M. J-. Moore, (Seal) Acting Commissioner of Patents.

